Air Conditioner Sizing Perth — Getting the Right kW for Your Room

An air conditioner that's too small struggles through a Perth summer; one that's too big short-cycles and wastes power. Correct sizing is the single biggest factor in comfort and running cost.

Why Size Matters

Capacity is measured in kilowatts (kW) of cooling. Undersized units run flat out on 40-degree days and never quite cool the room. Oversized units cool too fast, switch off, and leave the room humid and unevenly conditioned.

Rough Guide for Perth Homes

• Bedroom (up to 20m²): around 2.5–3.5kW
• Living area (20–40m²): around 5–6kW
• Open-plan living/kitchen (40–60m²): around 7–8kW

What Changes the Number

West-facing rooms, large windows, high ceilings and poor insulation all push the required capacity up — and Perth's afternoon sun makes orientation a big factor. A good installer will measure the room and account for these rather than guessing.

Get a Proper Assessment

Ask your installer to do a load calculation rather than quoting off a rule of thumb. The right size saves you money every summer for the life of the unit.